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Background Non-enveloped viruses, which lack a lipid envelope, display higher resistance to disinfectants, soaps and sanitizers compared to enveloped viruses. The capsids of these viruses are highly stable and symmetric protein shells that resist inactivation by commonly employed virucidal agents. This group of viruses include highly transmissible human pathogens such as Rotavirus, Poliovirus, Foot and Mouth Disease Virus, Norovirus and Adenovirus; thus, devising appropriate strategies for chemical disinfection is essential. Results In this study, we tested a mild, hypoallergenic combination of a denaturant, alcohol, and organic acid (3.2% citric acid, 1% urea and 70% ethanol, pH4) on two representative non-enveloped viruses – Human Adenovirus 5 (HAdV5) and Feline Calicivirus (FCV)– and evaluated the pathways of capsid neutralization using biophysical methods. The conformational shifts in the capsid upon chemical treatment were studied using Differential Scanning Calorimetry (DSC), while the morphological alterations were visualized concurrently using Transmission Electron Microscopy (TEM). We found that while treatment of purified HAdV5 particles with a formulation resulted in thermal instability and, large scale aggregation; similar treatment of FCV particles resulted in complete collapse of the capsids. Further, while individual components of the formulation caused significant damage to the capsids, a synergistic action of the whole formulation was evident against both non-enveloped viruses tested. Conclusions The distinct effects of the chemical treatment on the morphology of HAdV5 and FCV suggests that non-enveloped viruses with icosahedral geometry can follow different morphological pathways to inactivation. Synergistic effect of whole formulation is more effective compared to individual components. Molecular level understanding of inactivation pathways may result in the design and development of effective mass-market formulations for rapid neutralization of non-enveloped viruses.

We investigate the role of Tachyplesin (Tpl), a marine antimicrobial cell-penetrating peptide, as an anti-HBV agent. Our findings, using confocal microscopy and flow cytometry, demonstrate the internalization of FITC-Tpl in both Huh7 and HepG2 cell lines. Further, our results show that Tpl inhibits the expression of HBV proteins, including hepatitis B surface antigen (HBsAg) and hepatitis B ‘e’ antigen (HBeAg) in cell supernatants of human liver cell lines transfected with 1.3× pHBV. Interestingly Tpl also reduces levels of HBV pre-core RNA and HBV pregenomic RNA, suggesting that Tpl-mediated inhibition occurs at the early stages of HBV replication, including viral transcription. In addition, Tpl led to a significant reduction in levels of hepatitis B virion secretion. In sum, here we demonstrate the potent anti-HBV activity of Tpl at non-cytotoxic concentrations indicating the potential of Tpl to emerge as an effective therapeutic peptide against HBV.

Non-enveloped viruses, which lack a lipid envelope, typically display higher resistance to disinfectants, soaps and sanitizers compared to enveloped viruses. The capsids of these viruses are highly stable and symmetric protein shells that resist inactivation by commonly employed virucidal agents. This group of viruses include highly transmissible human pathogens such as Rotavirus, Poliovirus, Foot and Mouth Disease Virus, Norovirus and Adenovirus; thus, devising appropriate strategies for chemical disinfection is essential. We tested a mild combination of a denaturant, alcohol, and organic acid on two representative non-enveloped viruses – Human Adenovirus 5 (HAdV5) and Feline Calicivirus (FCV)– and evaluated the molecular pathway of capsid neutralization using biophysical methods. The transition temperatures signifying conformational shifts in the capsid were established in the presence and absence of chemical treatment using Differential Scanning Calorimetry (DSC), while the corresponding morphological alterations were visualized and correlated using Transmission Electron Microscopy (TEM). We found that while chemical treatment of purified HAdV5 particles resulted in increased thermal instability, followed by large scale particle aggregation; similar treatment of FCV particles resulted in complete collapse of the capsids. The distinct effects of the chemical treatment on the morphology of HAdV5 and FCV suggests that non-enveloped viruses with icosahedral geometry can follow different molecular pathways to inactivation. Further, while individual components of the chemical formulation caused significant damage to the capsids, a synergistic action of the whole formulation was evident against both non-enveloped viruses tested. Molecular level understanding of inactivation pathways may result in the design and development of effective mass-market formulations for rapid neutralization of non-enveloped viruses. formulation consisting of 3.2% citric acid, 1% urea in 70% ethanol, pH4 effectively inactivates HAdV5 and FCV. inactivation pathways with complete formulation, are different for the two viruses. effect of whole formulation is more effective compared to individual components.